netVOICE Power over Ethernet FAQ

What is Power over Ethernet (PoE)?

PoE is a technology for providing electrical power over the same cable used to connect equipment to the network. For more information, see the Wikipedia entry http://en.wikipedia.org/wiki/Power_over_Ethernet

Why would one use PoE?

There are two primary reasons for using PoE with VoIP:

• cabling is much simpler and cleaner with a single cable running from the phone to the network switch (i.e. no need for a separate power block and power wires)
• centralising power distribution with a central PoE switch makes it possible to connect the PoE switch to a UPS (Uninterruptible Power Supply) so that your VoIP phones will continue to operate even if your office experiences a power failure.

What phones support PoE?

Aastra, Linksys, Polycom, and Snom make phones that support PoE. You will need to check the specs for the particular phones you are interested in or contact netVOICE for guidance. Our Wiki page on How to Select an IP Phone (see http://wiki.netvoice.ca/doku.php?id=guide:phones) provides a list of some phone models that support PoE but understand that new models are introduced frequently and there may be new models that support PoE that have not yet been added to that Wiki page.

Note also that all Linksys devices (phones and analog telephone adapters) can be converted to operate with PoE by using the Linksys POES5 adapter.

What happens if I plug a non-PoE device into a PoE port?

Nothing. The industry standard for PoE requires the device providing power on the Ethernet cable send test signals to the connected equipment to ensure it is ready and able to accept power before actually enabling the power on the cable. If you connect a device that is not expecting power over the Ethernet cable into a PoE switch or injector no power will be provided and the device is safe.